1. Field of the Invention
The present invention relates to the field of pumping systems. In particular, the invention is concerned with an hydraulic pumping system having a soft start valve coupled with a pump outlet to provide reduced start pressure in order to reduce startup current of the electric motor coupled with the pump.
2. Description of the Prior Art
In a fluid pumping system, such as a hydraulic pump driven by an electric motor, the motor experiences high startup current until it achieves substantially synchronous speed. The startup current is even higher when the system starts with the pump under load or when low voltage conditions are present. High startup currents can overload circuits causing nuisance trips of the power supply.
Also, induction motors typically develop a startup torque that is lower than the synchronous speed running torque. For applications where the motor must start under full load, the load must be sized so that it does not exceed the available startup torque. In these instances the full running torque capability cannot be utilized. For a given load, a larger motor must be used to provide sufficient startup torque.